1. Field of the Invention
The present invention relates to an extruder for elastomeric material, and more particularly, to an extruder head for producing tire components.
2. Description of the Prior Art
There has been much development in extruder heads for thermoplastic resins and the like. However, elastomeric materials, such as rubber, are not easily extruded through conventional extruder heads. It must be noted that elastomeric materials must be processed at relatively high pressures, notably in the range of 1,000 to 10,000 p.s.i., compared to thermoplastic materials, and the temperature of the molten mass of elastomeric material must be controlled in a relatively narrow range of 210.degree. to 236.degree. F., for instance.
Thus, the extruder heads of the prior art for use with elastomeric materials are typically of heavy duty construction. Furthermore, in order to provide temperature control, cooling chambers and passages must be provided in the head. Various developments have been made in order to provide the necessary high pressure application and temperature control. An example of such developments is illustrated in U.S. Pat. No. 3,871,810, issued Mar. 18, 1975, and assigned to Uniroyal, Inc. In this patent, a driven roller forms a pressure chamber with the stationary portion of the head. The roller also includes the cooling passages.
Such extruder heads as well as other cast heads available in the tire making industry, compared to those available for extruding thermoplastic resin, are, as can be seen, cumbersome, difficult and expensive to construct and not easy to maintain.